1. Field of Invention
This invention relates to an adjustable roof support frame that may be used to support roofs with access holes.
2. Description of Related Art
Buildings, especially commercial buildings, are often required to have roof access holes to allow various objects and structures, such as heating, air conditioning, and ventilation ducts, electrical cables, pipes, skylights, and smoke stacks, to pass through their roofs. However, once a hole is cut into a roof, it is necessary to provide additional structural support around the hole. If no additional support is provided, the roof may be damaged or weakened when a load is applied to the roof.
Roof support frames have been developed to provide additional structural support to roofs with access holes. In general, support frames surround an access hole and transmit loads to adjacent trusses joists. However, support frames have been relatively expensive to manufacture and install. The requirements of each building and the dimensions of each access hole are different. Consequently, support frames have been custom designed and manufactured for each site. What has long been needed is a means by which one roof support may be adapted to be used in different situations and to fit access holes of many different sizes.
The design of most prior art roof support frames also requires the frames to be assembled in an off-site manufacturing facility. Many support frames are welded together then shipped to building sites and installed. However, the assembled frames are bulky, requiring a great deal of space, which significantly increase the shipping and handling costs. What has long been needed is a support frame that may be shipped unassembled and then easily assembled at a building site. This would reduce shipping and handling costs by allowing a greater number of frames to be shipped in the same space.
The deficiencies of the past are overcome by the present invention which provides a support frame for supporting roofs. In particular, the roof support frame of the present invention includes an adjustable roof support frame that may be used with a variety of different roofs. The adjustable roof support frame of the present invention can be advantageously used to support roofs having access holes of any of a variety of sizes. That is, the roof support frame can be adjusted to support the roof in a vicinity of an access hole of a particular size in a complimentary manner.
The roof support frame of the present invention also has cost savings advantages over the roof support frames of the past. Since all of the pieces are pre-fabricated, the instant invention advantageously avoids the need for fabrication steps of cutting or welding. Thus, the pieces can be mass produced. The needed pieces can be shipped unassembled as a compact package. The support frame can be assembled on site and adjusted to the desired size for installation. Furthermore, the individual supports of the support frame can be adjusted and fixed at desired lengths by fasteners that do not require special tools. Hence the overall frame and installation are typically less expensive than past roof support frames.
In one aspect, the roof support frame of the present invention advantageously has hooks for supporting lateral supports on roof trusses that the support frame spans. These hooks facilitate adjustment and assembly since the hooks support the lateral supports at the desired length while the fasteners are tightened. Alternatively, the hooks may be replaced by truss bridge members to interconnect the roof support frame to another roof support frame on an opposite side of one of the trusses. That is, a truss bridge member can be substituted for a hook, span a truss, and support a first lateral support of a first roof support frame and a first lateral support member of a second roof support frame on a truss that runs between the frames.
Other deficiencies of the past are also overcome as can be appreciated by a review of the descriptions and drawings set forth below.
The present invention comprises an adjustable roof support frame. The support frame comprises a first and a second lateral support and a first and a second cross support. The lateral supports and cross supports are attached together to form a substantially square or rectangular frame. Alternatively, other quadrilateral shapes may also be implemented.
Each lateral support comprises a first and second member that are adapted to be attached to each other. The second member comprises a substantially C-shaped cross section with a longitudinal channel. The channel is adapted to slidably receive the first member so that the inner top, side, and bottom surfaces of the channel abut the external top, side, and bottom surfaces of the first member, respectively. The overall length of the lateral supports may be adjusted by sliding the first member inside the channel of the second member. The first member may also have a C-shaped cross section with a longitudinal channel for increasing the rigidity of the member.
While C-shaped cross sections for the first and second members are preferred, other cross sections are also considered to be within the scope of the present invention. For example and not by way of limitation, these shapes may include I, H, square, rectangular, or solid beams.
Each member may comprise at least one fastener slot for receiving a fastener. When the first member is inside the channel of the second member, the fastener slots are aligned and a fastener can be inserted through the slots to attach the two members together. The fasteners are preferably standard nuts and bolts.
The cross supports are substantially similar to the lateral supports, having a first and second member. The second member has a substantially C-shaped cross section with a longitudinal channel. The second member slidably receives the first member within the longitudinal channel. Both the first and second members have at least one fastener slot for receiving a fastener.
The cross supports are attached to the lateral supports using joiners, preferrably in the form of L-brackets. The L-brackets abut the surfaces of the lateral supports and the cross supports. Fastener holes may be provided in the L-bracket to receive fasteners. When the cross supports are attached to the lateral supports, a square or rectangular hole is formed in the center of the frame. Objects and structures may be inserted through the hole to extend above or below the roof.
A truss hook is provided for attaching the support frame to trusses. In the preferred embodiment, one truss hook is attached to each end of each lateral support. The truss hook comprises a substantially T-shaped cross section with horizontal and vertical members. The horizontal and vertical members abut the upper and side surfaces of the lateral supports, respectively. The vertical member of the truss hook may comprise a fastener hole for attaching the truss hook to a lateral support. The end of the truss hook may have a hook for hooking the side of a truss.
The truss hook of the present invention may also be provided in the form of a truss bridge member that is adapted to span a truss and connect two support frames. The ends of the truss bridge member may have a substantially T-shaped cross section with horizontal and vertical members. The horizontal and vertical members abut the upper and side surfaces of the lateral supports of the support frames. Fastener holes may be provided in the vertical surface for receiving fasteners and attaching the lateral supports. The central portion of the truss bridge member is substantially horizontal with a small vertical height and is adapted to rest on a truss.
In another aspect, the invention is a kit for forming the adjustable roof support frame. The kit would generally include a minimum number of components. Typically the number of components would include enough pieces to complete at least one quadrilateral roof support frame. For example, a kit may include at least first and second lateral supports each comprising a first lateral member and a second lateral member having at least one slot adapted to adjustably connect the first lateral member to the second lateral member to provide a selected length for each lateral support. The kit also includes at least first and second cross supports each comprising a first cross member and a second cross member having at least one slot adapted to adjustably connect the first cross member to the second cross member to provide a selected length for each of the cross supports. In order to connect the cross supports to the lateral supports, the kit has at least four joiners. The support frame kit further includes at least four truss hooks for connection at the ends of the lateral supports. A plurality of appropriate fasteners is also included for interconnecting the supports, joiners, and truss hooks.
The above description sets forth, rather broadly, the more important features of the present invention so that the detailed description of the preferred embodiment which follows may be better understood and contributions of the present invention to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of claims. In this respect, before explaining at least one preferred embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangement of the components set forth in the following description or as illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.